Such cooling circuits are used in automotive engineering to dissipate heat from the internal combustion engine and to cool operating media of the internal combustion engine, such as, for example, exhaust gas, fresh gas, or lubricants, as a result of which the efficiency and/or the exhaust gas composition of the internal combustion engine can be influenced.
DE 10 2004 052 137 A1 shows a dual circuit cooling system for an internal combustion engine with a crankcase and a cylinder head. The crankcase is incorporated into the crankcase coolant circuit while the cylinder head is incorporated into a separate cylinder head coolant circuit. Both coolant circuits are fed from a common coolant pump. The crankcase coolant circuit can be closed by an actuating element, as a result of which the crankcase heats up more quickly after a cold start. Furthermore, it is possible to operate the two coolant circuits at different temperature levels.
DE 103 32 947 A1 likewise describes an internal combustion engine for a motor vehicle with a dual circuit cooling system in which the cylinder head and cylinder crankcase have separate coolant branches which are supplied from a coolant pump via a common feed. The coolant on the cylinder head and the cylinder crankcase, after exiting from the corresponding parts, is combined again and recirculated to the coolant pump. In so doing, the coolant can be routed alternately via one branch with the exhaust gas cooler, heat exchanger of the heating system, and oil cooler to the coolant pump or routed via a second branch alternately to the primary heat exchanger or bypassing the primary heat exchanger directly to the coolant pump.
However, the disadvantage is that the exhaust gas cooler for the illustrated coolant circuit can be supplied only with coolant which has already flowed through the entire engine, i.e., both the cylinder head and also the cylinder crankcase, and is heated accordingly. This results in efficiency losses in the cooling of the exhaust gas. Moreover, the integration of two different branches for return of the coolant to the coolant pump requires a large installation space.
The object of this invention is therefore to make available a cooling circuit for an internal combustion engine in which there can be a heat exchanger which can be operated as efficiently as possible for cooling of operating media of the internal combustion engine with low installation space requirements.